[Exercise] Triangle numbers divisors

def prime_factors(n):
d = 2
while (n > 1):
while (n%d==0):
yield d # Especially those
n /= d # two lines
d = d + 1

Ra8 wrote

arithma wrote@Ra8: That trick you have is pretty neat. How'd you think about it? (Referring to the }while(divs(n1)*divs(n2)<500);)

Well this works only in this case since n and n+1 will never have a common divisor.
if you had for example 4 ={1,2,4} and 6={1,2,3,6} 24={1,2,3,4,6,8,12,24} in this case it will not work because 2 is a common divisor

#include <iostream>
#include <string>
#include <vector>
#include <set>
#include <algorithm>
#include <cmath>
using namespace std;

int count_reused = 0;
int count_explord = 0;
set<int> primes;

int primePower(int64_t& n, int prime){
    int count = 0;
    
    while(n % prime == 0){
        
        int64_t multi = prime;
        int c = 1;
        while(n % (multi*multi) == 0){
            multi *= multi;
            c *= 2;
        }
        
        count += c;
        n /= multi;
    }
    
    return count;
}

int divs(int64_t n){
    int result = 1;
    int sqr = sqrt(n);
    
    set<int>::iterator itr = lower_bound(primes.begin(), primes.end(), sqr);
    if(itr == primes.end())
        itr--;
    
    while(n > 1){
        int prime = *itr;
        if(n % prime == 0){
            count_reused++;
            result *= primePower(n, prime) + 1;
        }
        
        if(itr == primes.begin())
            break;
        
        itr--;
    }
    
    int div = 2;
    while(n > 1 && div < n){
        if(n % div == 0){
            count_explord++;
            primes.insert(div);
            result *= primePower(n, div) + 1;
        }
        
        div++;
    }
    
    return result;
}

int main(){
    primes.insert(2);
    
    int64_t sum = 0;
    int i = 1;
    int64_t d;
    do {
        sum += i;
//        d = divs(sum);
        d = i % 2 == 0 ? divs(i/2)*divs(i+1) : divs((i+1)/2)*divs(i);
        if(i%1000==0){
            cout << i << " triangle numbers tried so far" << endl;
            cout << sum << " << triangle number max" << endl;
        }
        i++;
    } while (d < 1000);
    cout << "reused " << count_reused << endl;
    cout << "explored " << count_explord << endl;
    cout << "triangle# = " << sum << " & divisors = " << d << endl;
    cout << "largest prime " << *(primes.rbegin()) << endl;
    cout << "primes explored so far = " << primes.size() << endl;
    return 0;
}

public class TriangleNumber {
    public static boolean divNumber(int n){
        int counter=0;
        int sum=0;
        int end =(int) Math.sqrt(n);
        end++;//because looping to i<end is faster than looping to i<=end
        for(int i = 1 ; i < end; i++){
            if(n%i==0){
                counter+=2;
                sum+=i;
            }
        }
       
        if((counter>500)){
            System.out.println("the result is: "+n);
            return false;
        }

        else
            return true;
    }
    public static void main(String[] args){
       int val=0;
        int inc =0;
        boolean iterrate=true;
        while(iterrate){
            val+=inc;
            iterrate=divNumber(val);
            inc++;

        }

}
}

#include <iostream>
#include <cmath>
using namespace std;

int number_of_divisors(int n) {

    int count = 2;
    int square_root = sqrt(n);

    for (int i = 2; i <= square_root; i++)
        if (n%i == 0)
            count++; 

    return (n%square_root == 0) ? count*2-1 : count*2;

}

int main() {

    long n = 1; 
    for (int i = 2; number_of_divisors(n) <= 500; i++)
        n += i;

    cout << n << endl;
    return 0;

}

public class triangle {
	public static void main(String [] args){
		int count=0;
		int triangle=0;
		int factors=1;
		int test;
		while (factors <= 500){
                        count=count+1;
                        triangle=triangle+count;
                        factors=1;
                        for(int a=1;a<(Math.sqrt(triangle));a++){
                                test=triangle%a;
				if ( test == 0){
                                   factors=factors+2;
				}
			}
		}
	System.out.print(+triangle);
	}
}